Thanks to Kit Baum, a new Stata module, -rdci-, has been made available on
SSC (-ssc describe rdci-). -rdci- calculates risk difference confidence
intervals, that is, confidence intervals for the difference between two
independent proportions. The module calculates these confidence intervals
by each of four methods: Miettinen-Nurminen, Agresti-Caffo, Wallenstein and
Newcombe. These have been developed as alternatives to the Wald confidence
interval, which is what is reported by the official -cs- and -csi- commands.
Each of the alternatives is intended to provide improvement over the Wald
method, especially for small- or moderate-sized datasets.
The module contains two commands, -rdci- and -rdcii-, the latter an
immediate form of the former. They share basic syntax with -cs- and -csi-.
The commands call another user-written command, -ridder-, which must be
installed, as well (-findit ridders-). The module is accompanied by an
auxiliary do-file that illustrates its use.
Bug reports and suggestions for improvement are welcome.
Joseph Coveney
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